OAR@UM Collection:

Emerging plant health risks : a study of the risk of entry, establishment and spread of Xylella Fastidiosa spp. (Wells et al., 1987) in the Maltese territory

2022-05-27T07:22:50Z

Title: Emerging plant health risks : a study of the risk of entry, establishment and spread of Xylella Fastidiosa spp. (Wells et al., 1987) in the Maltese territory Abstract: Xylella fastidiosa (Wells et al., 1987) is considered as an important emerging plant health disease effecting European countries for the past years. Following the situation in the neighbouring countries and the yearly increase in trade of plant material, arises the need of appropriate measures to decrease the risk of introduction of the disease in the Maltese territory. The risk for introduction of Xylella fastidiosa in the Maltese territory was confirmed from three major pathways: plants for planting entering the PRA area from trade and imports, vectors, and the entry of passengers as carriers into the Maltese territory. Following the evaluation of the factors outlined, the probability of establishment of Xylella fastidiosa in the Maltese territory has been concluded as likely to happen with low levels of uncertainty. The pest risk analysis also confirms that spread by natural and human means throughout all the Maltese territory is likely to happen. Following the pest risk assessment, the level of risk in the pest risk analysis has been confirmed as moderate to likely. Several phytosanitary measures have been outlined after review of the existing measures including the effectiveness, technical feasibility and uncertainty of the measures proposed. The pest risk analysis will serve as a guideline in the implementation of the appropriate phytosanitary measures and the revision of the present phytosanitary measures. This study also offers possibilities for future studies on some of the phytosanitary measures proposed and updates which may arise due to more information on the disease and spread throughout the European Commission Description: M.SC.RURAL SCI.

Temporal analysis of ampelographic and physicochemical characteristics of the Maltese grapevine variety Girgentina

2022-05-27T07:21:16Z

Title: Temporal analysis of ampelographic and physicochemical characteristics of the Maltese grapevine variety Girgentina Abstract: The phenological stages, morphological characteristics, physicochemical parameters and mineral content of the Girgentina grapevine were determined over a two-year time course. Phenological and morphological characteristics were determined according to standardised OIV descriptors. Titratable acidity and pH were determined using an automatic titrator and the sugar content (Brix°) was determined by a refractometer. The total content of polyphenols in grapes was determined by using the Folin-Ciocalteu assay and a UV-Visspectrophotometer was used to determine the percentage of yellow, red and blue colour contribution, colour index, tint ratio, flavonoid ratio and total anthocyanins of grape samples. The concentration of minerals was determined by Microwave-Plasma Atomic Emission Spectroscopy. The temperatures at which important phenological stages occur, i.e. bud break (14°C), full bloom (20°C), full grape maturity (27°C) and beginning of wood maturity (28°C) were determined. Mean weight of grapes and leaves at harvest was approximately 4.00g and 3.70g respectively. Internodal distance increased along time (55.08 to 77.53mm). The mean acidity at harvest was 0.12g/100g and 0.16g/100g, pH was 3.62 and 3.86 and °Brix was 16.92 and 19.64 during the first and following year respectively. Spectroscopic analysis showed a progressive increase in red, blue, flavonoid ratio, anthocyanin content and colour index but a decrease in yellow and tint. Total polyphenolic content decreased along maturity and stood at 0.076±0.016%w/w and 0.064±0.024%w/w at the first and following year respectively. The concentration of Ca, Mg and Na showed an upward trend in both grapes and leaves. K showed an upward trend along the time course in grapes but a downward trend in leaves. Cu and Fe held a consistent concentration along time. The minerals in the highest concentration in both grapes and leaves were Na, Mg and K, followed by Cu, Fe and Ca in grapes and Ca, Cu and Fe in leaves. Pearson correlation revealed a low flavonoid ratio indicating a low content of anthocyanins. Principal Component Analysis (PCA) grouped grapevines by their sun orientation and segregated samples according to harvest year. Description: M.SC.RURAL SCI.

Cultivation of Goji berries (lycium barbarum and lycium ruthenicum) in the Maltese islands : an analysis of the main minerals and nutrients found in fresh berries

2022-05-27T07:19:31Z

Title: Cultivation of Goji berries (lycium barbarum and lycium ruthenicum) in the Maltese islands : an analysis of the main minerals and nutrients found in fresh berries Abstract: Fruit of Goji berries (Lycium spp.) have high nutrients, minerals, and bioactive compounds, and because of this, its cultivation in China and nearby regions dates back to over 4000 years. The increased demand for Goji berries has incentivised many other regions across the globe to explore different methods for its cultivation. This study provides a detailed account on the origin of Goji berries, the main regions cultivating this plant and whether the Maltese Islands are suitable for growing this plant. Different trials on methods of propagation (seeds, root cuttings and hard wood cuttings) of Lycium were conducted during a two-year study (2018-2020). A total of 36 Lycium barbarum plants were planted in four different locations in Malta and were irrigated with three types of water (rainwater, tap water and saline water). All plants managed to grow well and produce berries during this 2-year experiment. During 2018 a total of 5,485 grams of goji berries was produced from the 36 Lycium barbarum plants and 6,234 grams during 2019. During both 2018 and 2019 the Lycium barbarum plants planted in the ground and irrigated with tap water produced the highest amount of berries. An important factor that affected the total goji berry production was the daily number of sunlight hours. The goji berry trees planted in the locations that received 8 hours of direct sunlight during the spring and summer produced more berries than those that received less hours of direct sunlight. This study also analysed the fresh and dried goji berries produced in the Maltese Islands for the beneficial metals, proximate analysis, polyphenols and carotenoids. The results show that the goji berries cultivated in the Maltese Islands have good levels of Potassium (3717 to 7113 ppm), Polyphenols (0.06 to 0.15%w/w) and Carotenoids (0.007 to 0.13 mg/100ml). The methodology of the tests used in this study and the results were compared with those of other studies. Description: M.SC.RURAL SCI.

Morphological and physicochemical analysis of local varieties of prickly pears (Opuntia ficus-indica (L.) Mill.) from Malta

2022-05-27T07:16:37Z

Title: Morphological and physicochemical analysis of local varieties of prickly pears (Opuntia ficus-indica (L.) Mill.) from Malta Abstract: The prickly pear (Opuntia ficus-indica) is a drought resistant fruit-producing cactus that originated from Mexico but nowadays is widely found throughout the world. While locally, prickly pears have been neglected despite their huge potential in surviving ahrsh conditions, in other parts of the world, large industries were developed in manufacturing products from prickly pears. This study aimed to characterise morphologically and physiochemically local prickly pear varieties in order to safeguard these varieties and prevent the loss of more varieties. For this study, a total of eight varieties spread over fifteen accession found within the largest prickly pear collection found in Malta were studied, where each variety being represented by three/four trees. The morphological assessment investigated the fruit and its peel and one-year-old cladodes which included dimentions, weight and thickness among others. UV-Vis absorbance was determined through spectroscopy. The %yellow, %red and %blue in the fruit pulp were found between 88.4 – 96.8, 1.95 – 5.61 and 1.22 – 3.75 respectively. Colour density, tint, flavonoid and anthycyanin contents were also determined. Total polyphenol content was measured between 0.332 – 1.09 %w/w GAE DM in the pulp of fruit and 0.681 – 1.69 %w/w GAE DM in the peel of fruit using Folin-Ciocalteu assay. Total acidity of fruit pulp was determined by titration was found between 73.5 – 167 mg/100g (expressed as citric acid). Dry matter content in prickly pear fruit pulp, peel and cladode were found between 2.61 – 5.9%, 8.32 – 15.22% and 5.79 – 14.11% respectively. Nutritional composition (Ca, Cr, Cu, K, Mg, Na, Zn) of prickly pear fruit pulp, peel and one-year-old cladodes were determined through digestion followed by Microwave-Plasma Atomic Emission Spectroscopy. Proximate analysis of the one-year-old cladodes which was carried out via N-IR Spectrophotometer constituted mainly of starch (0.28 – 3.34% FW), while fat was very low (<0.01% FW). Based on quantitative parameters, three Principal Component Analysis (PCAs) were performed for morphology, physicochemical and nutritional parameters. The weight and dimentions of fruit correlated strongly the most within the variability in the morphological PCA. As for the physicochemical PCA, the three colours correlated strongly the most to describe the variability, with some of the rvalues measured at 1.000 and -1.000. As for the nutritional PCA,all the minerals described the variability especially Ca and Mg. In addition, the strongest positive correlations occured with minerals within the same plant part followed by correlations between the peel of fruit and cladodes. A dichotomous key was created successfully based on quantitative and visual parameters assessed. This key is solely based on the varieties assessed in this study. Conclusively, despite that fact that this study took a horizontal way of assessing the local prickly pears, several important factors were determined which can unlock the potential of these varieties. Such data has revealed the potential of these prickly pears for geneti breeding, conservation programs and the establishment of its cultivation for various uses as the market demands. Description: M.SC.RURAL SCI.